Do not limit your searches to a wedding photo of a couple. Create its history with the help of the marriage certificate, invitations, photos of the priest and place of their wedding. For example, in the nineteenth century, you could buy pre-printed forms, where you could place small photos of the bride, groom, and in some cases of the priest with the date and the place of incident. They were convenient to place in frames and to hang up on walls. In your family you can also find things, which will complete the story, including cloths or wedding dresses. In some families a part of wedding traditions are the quilted blankets.
Never stop searching for photos to find out visible history of people on yours family tree. Only, because the image doesn't look like a wedding photo, does not mean it's not, until you find the time to identify the date of the print and to compare it to the known date of wedding. Only when I decided to define dates of my grandmother's photos, I have found out, that one of those was made on the day of her wedding. In 1912, my Grandmother Alice MacDuff got married in a beautiful dress with big buttons. As it was not a traditional white dress, I have not recognized a wedding portrait. Only after I had researched the information about the photographer, had heard the family stories, had found the marriage certificate and had precicely researched the photo, I have found the correct answer. It was a small detail. The photographer placed her, the light to be reflected from a surface of her new wedding ring. There is an accompanying portrait of my grandfather also dressed in a new costume, standing, his ring to be visible.
If you can not find a wedding photos of your ancestors, there are reasons for this. Not everyone could afford the photographer in the middle 19th century. In some families the absence of wedding images can point to a conflict of some kind, like parental disapproval or a secret escape.
As soon as the wedding portrait gets to your hands, even if it doesn't, try to find the image of the church or even of the priest. David Lambert, the librarian of the Historical Genealogical Society in New England, knew, that Reverend Robert Cassy Waterston has betrothed his greatgrandparents Alexander Livingstone Pua and Ann Whitney Faggins in a chappel on Pitts Street, Massachusets on January, 28th, 1844, but he did not have their photo. He has found an engraving of church in the town directory, got a copy of their marriage certificate, and, to his surprise has found a photo of the priest, who had married them in a local antique shop. Now he's got an illustrated history of a marriage, without having a photo of a couple though. Though David could not find a photo of his greatgrandparents, he could restore the feeling of romance with the help of other images and documents. Combining everything, you can tell a history of the ancestors with the help of a history of their love. Who knows, probably, it can inspire you to write the next bestseller based on the histories of their life.